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Tytuł:
An experimental method for estimating the thermal diffusivity of building elements, depending on the resolution of temperature measurement
Autorzy:
Owczarek, Mariusz
Powiązania:
https://bibliotekanauki.pl/articles/132057.pdf
Data publikacji:
2019
Wydawca:
Centrum Rzeczoznawstwa Budowlanego Sp. z o.o.
Tematy:
thermal diffusivity
physical properties
Opis:
Thermal diffusivity, also known as temperature equalization coefficient, is the basic parameter in the Fourier equation for non-stationary heat exchange. Its values are known for homogeneous materials with a specific composition. Building elements made of reinforced concrete, for example, have a heterogeneous structure. For such cases, table values from the literature may differ significantly from the specific object for in real constructions. More accurate thermal diffusivity values can be obtained from measurements for a given element. Since these are usually large sized elements, the measurement method should take into account the material in the entire volume of the element. Proposals for such a method based solely on temperature measurement at several depths in the sample were presented. It consists in solving the inverse problem assuming a polynomial solution of the Fourier equation. An attempt was made to validate the method through a numerical experiment. Temperature variability was simulated with one-dimensional flow in the wall with assumed thermal diffusivity. Then the value of this diffusivity was determined from the calculated temperatures. On the inside of the partition, a constant temperature was maintained and on the outside it changed periodically. The dependence of the error in the obtained diffusivity value on the precision of temperature results was analyzed. Depending on the precision of the calculations, a minimum relative error of 2 to 6 percent was obtained. With the help of the data presented in the article, conclusions can be drawn as to the conditions that must be met to determine the value of diffusivity in real measurements with the required accuracy. The obtained results indicate that this method is worth further research.
Źródło:
Modern Engineering; 2019, 1; 28-33
2450-5501
Pojawia się w:
Modern Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Thermal conductivity of food products
Przewodność cieplna produktów spożywczych
Autorzy:
Aerlichman, V.N.
Fatychov, J.A.
Kukelka, L.
Kopec, A.
Powiązania:
https://bibliotekanauki.pl/articles/35494.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Instytut Agrofizyki PAN
Tematy:
food product
thermal conductivity
thermal diffusivity
thermal diffusivity coefficient
heat conductivity coefficient
Opis:
The presented work is focused on the food thermal characteristics calculation methods (heat conductivity coefficient and thermal diffusivity coefficient a). Thermal characteristics of food are important in food industry and define the intensiveness of technological processes of food refrigeration and thermal treatment, energy consumption for their realization and technological equipment production rate. They are also needed for the building and validation of mathematical models of heat transfer in food products which are useful in the design and optimisation of freezing, heating, cooking and cooling pro-cesses and equipment. It is not easy to define the food thermal characteristics. Difficulties arise from their heterogeneity, high labour consumption and complexity of experimental sets. Methods for experimental determination of heat conductivity coefficient and thermal diffusivity coefficient a based on the regular method mode require the α → ∞ condition, which is the case of high speed of the environment which flows around the test sample, as in the case of boiling or condensing. Using the method presented in this article it is possible to determine the heat conductivity and thermal diffusivity coefficient a even in the absence of the condition α → ∞.
W pracy opisano metodę pozwalającą na obliczeniowe wyznaczenie charakterystyk cieplnych produktów spożywczych – współczynnika przewodzenia ciepłaoraz współczynnika wyrównania temperatury (dyfuzyjności cieplnej) a. Współczynniki te wpływają na przebieg procesów obróbki termicznej produktów, a także na zużycie energii i produktywność urządzeń technologicznych. Znajomość tych współczynników jest konieczna do tworzenia modeli matematycznych wymiany ciepła w produktach spożywczych, użytecznych w projektowaniu i optymalizacji procesów i urządzeń do mrożenia, ogrzewania, gotowania czy schładzania produktów. Określenie właściwości cieplnych żywności nie jest łatwe. Trudności wynikają z różnorodności produktów spożywczych, pracochłonności i złożoności stanowisk badawczych. Sposoby eksperymentalnego wyznaczania ww. współczynników oparte na metodzie stanu uporządkowane-go wymagają spełnienia warunku α→∞, co ma miejsce w przypadku dużych prędkości środowiska omywającego badaną próbkę, przy gotowaniu lub kondensacji. Za pomocą przedstawionej w pracy metody możliwe jest wyznaczenie współczynnika przewodzenia ciepła i współczynnika dyfuzyjności cieplnej a nawet w przypadku braku spełnienia warunku α→∞.
Źródło:
Acta Agrophysica; 2014, 21, 2
1234-4125
Pojawia się w:
Acta Agrophysica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Synthesis and Characterization of Thermal Properties of Type Eu2O3-ZrO2 Sinters
Autorzy:
Jucha, S.
Moskal, G.
Mikuśkiewicz, M.
Powiązania:
https://bibliotekanauki.pl/articles/352258.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
pyrochlores
europium zirconates
thermal diffusivity
TBC
Opis:
The oxides with pyrochlore or defected fluorite structure are a potential alternative ceramic materials for now widely used yttria-stabilized zirconia 8YSZ in the application for the insulation layer of thermal barrier coatings systems. This paper presents a procedure of synthesis of europium zirconate of Eu2Zr2O7 type, by the method of high temperature sintering under pressure. The analysis of the effect of the powders` homogenization methods on homogeneity of final sintered material showed that the highest homogeneity can be obtained after mechanical mixing in alcohol. Moreover, the DSC investigation carried out on a mixture of powders before the sintering process and on the material after high temperature sintering under pressure, suggest the synthesis of a new phase an europium zirconate Eu2Zr2O7 with the pyrochlore structure. Obtained phase was characterized by stability over the entire range of tested temperature, i.e. to 1450°C. The resulting material based on europium zirconate has a lower coefficient of thermal diffusivity than the now widely used 8YSZ.
Źródło:
Archives of Metallurgy and Materials; 2016, 61, 2B; 1121-1128
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Copper-Carbon Nanoforms Composites - Processing, Microstructure and Thermal Properties
Autorzy:
Pietrzak, K.
Gładki, A.
Frydman, K.
Wójcik-Grzybek, D.
Strojny-Nędza, A.
Wejrzanowski, T.
Powiązania:
https://bibliotekanauki.pl/articles/350995.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
metal matrix composite
sintering
copper
graphene
thermal diffusivity
Opis:
The main current of publication is focused around the issues and problems associated with the formation of composite materials with Cu matrix and reinforcing phases in the various carbon nanoforms. The core of the research has been focused on thermal conductivity of these composites types. This parameter globally reflects the state of the structure, quality of raw materials and the technology used during the formation of composite materials. Vanishingly low affinity of copper for carbon, multilayered forms of graphene, the existence of critical values of graphene volume in the composite are not conducive to the classic procedures of composites designing. As a result, the expected, significant increase in thermal conductivity of composites is not greater than for pure copper matrix. Present paper especially includes: (i) data of obtaining procedure of copper/graphene mixtures, (ii) data of sintering process, (iii) the results of structure investigations and of thermal properties. Structural analysis revealed the homogenous distribution of graphene in copper matrix, the thermal analysis indicate the existence of carbon phase critical concentration, where improvement of thermal diffusivity to pure copper can occur.
Źródło:
Archives of Metallurgy and Materials; 2017, 62, 2B; 1307-1310
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A Method Of Calculating Thermal Diffusivity And Conductivity For Irregularly Shaped Specimens In Laser Flash Analysis
Autorzy:
Szałapak, J.
Kiełbasiński, K.
Krzemiński, J.
Młożniak, A.
Zwierkowska, E.
Jakubowska, M.
Pawłowski, R.
Powiązania:
https://bibliotekanauki.pl/articles/220433.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
thermal diffusivity
LFA
LTJT joints
high power electronics
Opis:
The Low Temperature Joining Technique (LTJT) using silver compounds enables to significantly increase the thermal conductivity between joined elements, which is much higher than for soldered joints. However, it also makes difficult to measure the thermal conductivity of the joint. The Laser Flash Analysis (LFA) is a non-intrusive method of measuring the temperature rise of one surface of a specimen after excitation with a laser pulse of its other surface. The main limitation of the LFA method is its standard computer software, which assumes the dimensions of a bonded component to be similar to those of the substrate, because it uses the standard Parker’s formula dedicated for one-dimensional heat flow. In the paper a special design of measured specimen was proposed, consisting of two copper plates of different size joined with the sintered silver layer. It was shown that heat properties of these specimens can also be measured after modifying the LFA method. The authors adapted these specimens by masking the false heat signal sourced from the uncovered plate area. Another adaptation was introducing a correcting factor of the heat travel distance, which was calculated with heat-flow simulations and placed into the Parker’s formula. The heat-flow simulated data were compared with the real LFA measurement results, which enabled estimation of the joint properties, e.g. its porosity.
Źródło:
Metrology and Measurement Systems; 2015, 22, 4; 521-530
0860-8229
Pojawia się w:
Metrology and Measurement Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analysis of metrological conditioning of thermal diffusivity measurements applying modified Angstroms method at scanning mode operation
Autorzy:
Panas, A. J.
Nowakowski, M.
Powiązania:
https://bibliotekanauki.pl/articles/242228.pdf
Data publikacji:
2011
Wydawca:
Instytut Techniczny Wojsk Lotniczych
Tematy:
thermal diffusivity
thermophysical properties
temperature oscillation
modified Angstrom technique
Opis:
A technique of the temperature dependent thermal diffusivity investigation has been analysed. The technique is based on the modified Angstrom method utilising periodic temperature oscillations in a slab specimen. The additional modification consists of imposing linear temperature changes - application of linear scans. This scanning mode procedure enables investigation of the thermal diffusivity over a certain temperature interval. The thermal diffusivity is calculated independently from two relations based on the measured amplitude attenuation and the measured phase shift of the temperature oscillation passing through the investigated specimen. The paper discuses the problem of the thermal diffusivity identification uncertainty. As a result correction factors for the thermal diffusivity data derived from simplified formulae have been determined. The procedure of the thermal diffusivity measurement has been verified by numerical modelling. Comparison between the initial and response signals with illustration of the linear scan imposed to a basic oscillation with reference to a classical procedure of subsequent steps, illustration of the approximation error analysis methodology and results in the form of a thermal diffusivity correction factor, comparison between the uncorrected and corrected applying in numerical modelling of the temperature oscillation experiment are presented in the paper.
Źródło:
Journal of KONES; 2011, 18, 2; 339-347
1231-4005
2354-0133
Pojawia się w:
Journal of KONES
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of winter wheat on soil thermal properties of a Paleudalf
Autorzy:
Haruna, S.I.
Powiązania:
https://bibliotekanauki.pl/articles/2082568.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Instytut Agrofizyki PAN
Tematy:
thermal conductivity
volumetric heat capacity
thermal diffusivity
soil organic carbon
Opis:
Soil thermal properties can influence several soil processes important for crop productivity. This study was conducted to evaluate the influence of cover crops on selected soil physical and thermal properties. The field site was set up using a randomized complete block design with two levels of cover crops (cover crops versus no cover crops). The soil thermal properties measured included thermal conductivity, volumetric heat capacity, and thermal diffusivity. The physical properties of the soil studied included bulk density, volumetric water content, total pore spaces, water-filled pore spaces, air-filled pore spaces, gas diffusion coefficient, and soil pore tortuosity factor. Soil organic carbon was also measured. The results showed that soil organic carbon was 26% higher under cover crops management compared to no cover crops management. Thermal conductivity and thermal diffusivity were positively correlated with soil bulk density and these properties (soil thermal conductivity and soil thermal diffusivity) were higher under no cover crops management compared with cover crops management probably due to the proximity between soil particles. The volumetric heat capacity was positively correlated with soil organic carbon, with soil organic carbon being higher under cover crops management compared with no cover crops management. Results from the current study show that cover crops can improve soil physical and thermal properties which may benefit crop productivity as corroborated via laboratory measurements.
Źródło:
International Agrophysics; 2019, 33, 3; 389-395
0236-8722
Pojawia się w:
International Agrophysics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Investigation of thermal properties of novel phase change material mixtures (octadecane-diamond) with laser flash analysis
Autorzy:
Sierakowski, Mateusz
Godlewski, Wojciech
Domański, Roman
Kapuściński, Jakub
Wiśniewski, Tomasz
Kubiś, Michał
Powiązania:
https://bibliotekanauki.pl/articles/246255.pdf
Data publikacji:
2019
Wydawca:
Instytut Techniczny Wojsk Lotniczych
Tematy:
phase change materials
PCM
diamond powder
thermal conductivity
thermal diffusivity
Opis:
Phase change materials (PCMs) are widely used in numerous engineering fields because of their good heat storage properties and high latent heat of fusion. However, a big group of them has low thermal conductivity and diffusivity, which poses a problem when it comes to effective and relatively fast heat transfer and accumulation. Therefore, their use is limited to systems that do not need to be heated or cooled rapidly. That is why they are used as thermal energy storage systems in both large scale in power plants and smaller scale in residential facilities. Although, if PCMs are meant to play an important role in electronics cooling, heat dissipation, or temperature stabilization in places where the access to cooling water is limited, such as electric automotive industry or hybrid aviation, a number of modifications and improvements needs to be introduced. Investigation whether additional materials of better thermal properties will affect the thermal properties of PCM is therefore of a big interest. An example of such material is diamond powder, which is a popular additive used in abradants. Its thermal diffusivity and conductivity is significantly higher than for a pure PCM. The article presents the results of an analysis of the effect of diamond powder on thermal conductivity and diffusivity of phase change materials in the case of octadecane.
Źródło:
Journal of KONES; 2019, 26, 4; 211-218
1231-4005
2354-0133
Pojawia się w:
Journal of KONES
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Investigation of the effect of diamond powder on the thermal properties of octadecane using differential scanning calorimetry
Autorzy:
Godlewski, Wojciech
Sierakowski, Mateusz
Domański, Roman
Kapuściński, Jakub
Powiązania:
https://bibliotekanauki.pl/articles/242378.pdf
Data publikacji:
2019
Wydawca:
Instytut Techniczny Wojsk Lotniczych
Tematy:
phase change materials
PCM
diamond powder
thermal conductivity
thermal diffusivity
Opis:
The purpose of this work was to examine the effect of diamond powder on the thermal properties of phase change materials on the example of octadecane. The experiment involved mixing of diamond powder with a specific granulation with the aforementioned representative of the alkanes group. Two different grain sizes were used: 50 and 250 micrometres. The change of specific heat, latent heat of phase change and degree of supercoiling in newly formed mixtures was compared to the pure forms of the phase-change materials used. Initial mixing with a glass-stirring rod showed strong stratification for each granulation due to the low viscosity of the mixture and too large differences between component densities. It was decided to add amorphous silicon dioxide to the mixtures, which increases density of the mixture. The optimal percentage of amorphous silicon dioxide was estimated experimentally. Measurements of thermal parameters were carried out using DSC technology. The results of the tests of specific heat and latent phase transition heat showed that with the increasing content of diamond, the specific heat of the mixture decreases almost twice, and the latent heat can decrease by up to three times. The effect of diamond powder on reducing the degree of supercoiling of the mixture was also observed. An important observation was that the mixture with higher granulation of diamond powder had greater tendency for sedimentation. This method could be used to increase thermal conductivity and diffusivity of phase change materials and make them viable for use in systems that require cooling at high rate or temperature stabilization, such as control systems in electronic vehicles or aviation industry and at the same time decrease the degree of supercoiling which could increase the efficiency of system.
Źródło:
Journal of KONES; 2019, 26, 3; 39-45
1231-4005
2354-0133
Pojawia się w:
Journal of KONES
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Study of the periodic thermal contact between exhaust valve and its seat in an internal combustion engine
Autorzy:
Zemmouri, Amina
Azzouz, Salaheddine
Benchadli, Djillali
Ayad, Amar
Chaoui, Kamel
Powiązania:
https://bibliotekanauki.pl/articles/24200828.pdf
Data publikacji:
2023
Wydawca:
Polska Akademia Nauk. Polskie Naukowo-Techniczne Towarzystwo Eksploatacyjne PAN
Tematy:
seat thermal behavior
contact surface evolution
contact surface topography
thermal diffusivity
Opis:
The focus of internal combustion engine development for urban vehicles is shifting towards reducing materials by making them lighter. In order to maintain thermal and flow levels, a model was developed to study the thermal behavior of valve seats during periodic contact, which can also help improve engine performance and fuel efficiency. The model, composed of two cylindrical bars in periodic contact, takes into account the evolution and topography of the contact surface. The model's performance was evaluated through various experimental studies and showed a maximum difference of 5.05% with experimental values, in good agreement with previous literature. The results showed that heat flux increases with increasing contact frequency and thermal diffusivity affects conductive transfer. This model can be used by manufacturers to evaluate cylinder head temperature and by the automotive industry to improve heat transfer in engines.
Źródło:
Eksploatacja i Niezawodność; 2023, 25, 2; art. no. 162911
1507-2711
Pojawia się w:
Eksploatacja i Niezawodność
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Investigations of Thermal Diffusivity of Material of Compressor Blade of Turbine Jet Engine Using Modified Temperature Oscillation Method
Badania dyfuzyjności cieplnej materiału łopatki sprężarki turbinowego silnika odrzutowego metodą wymuszenia okresowego
Autorzy:
Omen, Ł.
Panas, A.
Powiązania:
https://bibliotekanauki.pl/articles/403404.pdf
Data publikacji:
2018
Wydawca:
Wojskowa Akademia Techniczna im. Jarosława Dąbrowskiego
Tematy:
mechanics
thermal diffusivity
Ångström’s method
dyfuzyjność cieplna
metoda Ångströma
Opis:
The modified temperature oscillation method was applied for investigation of thermal diffusivity of the aviation turbine engine’s part. The studies resulted in characterization of the applied method and experimental procedures performance. They were motivated by a need of determination of thermophysical data of the investigated material. The acquired thermal diffusivity data enabled identification of the material’s type and will be applied as input data for numerical analyses on thermo-mechanical loads of the structure. The investigated specimen was a sample of material from the first stage compressor’s blade of the AŁ-21F3 turbine engine. The measurements were conducted within the range of 5°C to 95°C. The thermal diffusivity was calculated from both the amplitude and phase responses to the harmonic excitation from exact analytical solution of the appropriate heat conduction problem. The appropriate transcendental equations describing the response signal amplitude attenuation and phase shift were solved applying iterative procedures. The analysis confirmed the effectiveness of the research methods and enabled to identify the material as titanium alloy.
W pracy omówiono wykorzystanie zmodyfikowanej metody wymuszeń okresowych do określenia dyfuzyjności cieplnej materiału konstrukcyjnego lotniczego silnika odrzutowego oraz przedstawiono zastosowane procedury badań. Bezpośrednią przyczyną podjęcia badań była konieczność identyfikacji i udokumentowania danych materiałowych do ich późniejszego wykorzystania w modelowaniu numerycznym obciążeń termomechanicznych konstrukcji. Długofalowo wykonane badania mają służyć opracowaniu szybkiej i skutecznej nieniszczącej metody określania właściwości cieplnofizycznych elementów konstrukcyjnych napędów lotniczych. Obiektem badań była próbka materiału pobrana z łopatki wirnikowej pierwszego stopnia sprężarki turbinowego silnika odrzutowego AŁ–21F3. Badania wykonano dla przedziału temperatury od 5 °C do 95 °C. Wartość dyfuzyjności cieplnej określono wykorzystując tzw. amplitudowe i fazowe cechy odpowiedzi na wymuszenie quasi-sinusoidalne. Analiza otrzymanych wyników potwierdziła skuteczność zastosowanej metody badań i pozwoliła na zidentyfikowanie badanego materiału, jako stopu tytanu.
Źródło:
Problemy Mechatroniki : uzbrojenie, lotnictwo, inżynieria bezpieczeństwa; 2018, 9, 1 (31); 79-92
2081-5891
Pojawia się w:
Problemy Mechatroniki : uzbrojenie, lotnictwo, inżynieria bezpieczeństwa
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Determination of thermal diffusivity values based on the inverse problem of heat conduction - numerical analysis
Autorzy:
Adamowicz, Adam
Powiązania:
https://bibliotekanauki.pl/articles/2204678.pdf
Data publikacji:
2022
Wydawca:
Politechnika Białostocka. Oficyna Wydawnicza Politechniki Białostockiej
Tematy:
thermal diffusivity
inverse heat conduction problem
impulse heating
finite element analysis
Opis:
This paper presents a discussion on the accuracy of the method of determining the thermal diffusivity of solids using the solution of the inverse heat conduction equation. A new measurement data processing procedure was proposed to improve the effectiveness of the method. Using the numerical model, an analysis of the sensitivity of the method of thermal diffusivity determination to changes in operational and environmental parameters of the test was carried out. The obtained results showed that the method was insensitive to the parameters of the thermal excitation impulse, the thickness of the tested sample, and the significant influence of convection cooling on its accuracy. The work was completed with the formulation of general conclusions concerning the conditions for determining the thermal diffusivity of materials with the use of the described method.
Źródło:
Acta Mechanica et Automatica; 2022, 16, 4; 399--407
1898-4088
2300-5319
Pojawia się w:
Acta Mechanica et Automatica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Synthesis, Characterization and Thermal Diffusivity of Holmium and Praseodymium Zirconates
Autorzy:
Stopyra, M.
Niemiec, D.
Moskal, G.
Powiązania:
https://bibliotekanauki.pl/articles/352244.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
pyrochlores
synthesis
polymerized-complex method
holmium zirconate
praseodymium zirconate
thermal diffusivity
Opis:
A2B2O7 oxides with pyrochlore or defected fluorite structure are among the most promising candidates for insulation layer material in thermal barrier coatings. The present paper presents the procedure of synthesis of holmium zirconate Ho2Zr2O7 and praseodymium zirconate Pr2Zr2O7 via Polymerized-Complex Method (PCM). Thermal analysis of precursor revealed that after calcination at relatively low temperature (700°C) fine-crystalline, single-phase material is obtained. Thermal diffusivity was measured in temperature range 25-200°C, Ho2Zr2O7 exhibits lower thermal diffusivity than Pr2Zr2O7. Additionally, PrHoZr2O7 was synthesized. The powder in as-calcined condition is single-phase, but during the sintering decomposition of solid solution took place and Ho-rich phase precipitated. This material exhibited the best insulating properties among the tested ones.
Źródło:
Archives of Metallurgy and Materials; 2016, 61, 2B; 1249-1254
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Thermophysical properties of the Sołtmany meteorite
Autorzy:
Szurgot, M.
Wach, R. A.
Przylibski, T.A.
Powiązania:
https://bibliotekanauki.pl/articles/411496.pdf
Data publikacji:
2012
Wydawca:
Polskie Towarzystwo Meteorytowe
Tematy:
chondrite
differential scanning calorimetry (DSC)
specific heat capacity
thermal capacity
thermal diffusivity
thermal conductivity
Opis:
Bulk density, porosity and thermophysical properties of the Sołtmany meteorite have been determined. The mean bulk density of the meteorite is 3.475‧103kg/m3, mean bulk density of the crust is 4.3‧103 kg/m3, grain density 3.71‧103 kg/m3, and porosity 6.4 ±} 0.4%. Mean specific heat capacity determined by DSC in temperature range between 223 and 823 K increases from 595 to 1046 J/(kg‧K), and is equal to 728 J/(kg‧K) at room temperature. Specific heat capacity of various samples is in the range 705–769 J/(kg‧K) at room temperature. Thermal capacity of Sołtmany chondrite is equal to 2.53‧106 J/(m3‧K), thermal diffusivity (1.5–1.8)‧10-6 m2/s, and thermal conductivity 3.9–4.5 W‧m–-1‧K-1at room temperature. Differential scanning calorimetry revealed two reversible phase transitions in the Sołtmany’s troilite: α/β transition at 423 K, and β/γ transition at 596.6 K.
Źródło:
Meteorites; 2012, 2, No. 1-2; 53-65
2299-0313
2299-1220
Pojawia się w:
Meteorites
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Wykorzystanie metody Ǻngströma do szacowania dyfuzyjności cieplnej wsadu w układzie nagrzewania indukcyjnego
Utilisation of Ǻngström method for estimating a thermal diffusivity of charge in induction heating setup
Autorzy:
Cieślak, A.
Zgraja, J.
Powiązania:
https://bibliotekanauki.pl/articles/407956.pdf
Data publikacji:
2015
Wydawca:
Politechnika Lubelska. Wydawnictwo Politechniki Lubelskiej
Tematy:
dyfuzyjność cieplna
właściwości materiałowe
nagrzewanie indukcyjne
thermal diffusivity
material properties
induction heating
Opis:
Przedmiotem niniejszej pracy było poszukiwanie metody szacowania dyfuzyjności cieplnej wsadu nagrzewanego indukcyjnie. Przedstawiono próbę wykorzystania metody ÅNGSTRÖMA w układzie, w którym wymuszenie generowano metodą indukcyjną. Analiza objęła zagadnienie wrażliwości badanej metody na wybrane parametry układu. Zaprezentowane wyniki pokazują, że przy zachowaniu odpowiednich wymiarów geometrycznych próbki oraz odpowiednio rozmieszczonych punktów pomiarowym możliwe jest uzyskanie wyników szacowania dyfuzyjności cieplnej z poziomem błędu poniżej 50%.
Main aim of this article is to find method for determination thermal diffusivity of induction heated charge. Unique try of utilisation ÅNGSTRÖM’s method and it’s sensitivity on various parameters of setup was presented. Summary allows to say that with respect to shown precautions it is possible to achieve results on satisfactory level of accuracy.
Źródło:
Informatyka, Automatyka, Pomiary w Gospodarce i Ochronie Środowiska; 2015, 2; 35-38
2083-0157
2391-6761
Pojawia się w:
Informatyka, Automatyka, Pomiary w Gospodarce i Ochronie Środowiska
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 47

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